1. Field of the Invention
The present invention relates to oil well downhole tools and more particularly relates to an improved method for placing a sand control media such as a gravel pack, in a through tubing situation where restrictions need to be passed, wherein collapsible stand off devices are used for creating an annulus between the tool and the internal wall of the casing where sand control media can reside and wherein the stand off devices collapse so that the tool hub can pass through restricted diameters such as production tubing, nipples, pressure control devices, packer bores, valves and the like.
2. General Background
Sand control is required in many oil and gas wells wherein sand enters the wellbore during well production. The sand then flows into the well annulus with the flowing oil and sand creating an abrasive problem. One of the methods of controlling such a problem is through the use of a gravel pack, which is simply a gravel filled portion of the wellbore that serves as a filter mass preventing sand from being carried by produced fluids into the well strainer or perforated liner thus producing mechanical abrasive action that destroys downhole metal parts of the well.
Other problems that relate to sand production include "sanding up" of the wellbore which can eliminate production from perforations below the top of the sand. Sand bridging can occur in the casing or tubing and this shuts off all flow from the perforations. Further, the erosion of sand from surrounding formation can cause damage to the casing because of this loss of formation support. Similarly, casing damage can result from subsidence. Further, sand production creates abrasion at the surface in hydrocarbon processing equipment that is positioned at the well head.
Many patients have been issued relating to methods and apparatus for installing gravel packs. Other patents relate to the discharging of material such as sand or cement in the well. An early patent entitled "Method of Graveling Wells" is U.S. Pat. No. 2,452,654 issued to Hayes. In the Hayes patent, a method of gravel packing a well includes the placing of a granular material in that portion of the well bore within the producing formation and shooting bullets from within the well bore through the granular material into the formation, the suction back of the bullets causing some of the granular material to be pulled into the tubular spaces in back of the bullets. Another early patent that relates to setting a gravel pack in a well is the Baker U.S. Pat. No. 2,707,998 entitled "Setting Tool, Dump Bailer and Well Packer Apparatus".
Another early patent relating to the discharging of a control media into a well is discussed in the Fultz U.S. Pat. No. 2,526,021 entitled "Apparatus For Discharging Viscous Liquids In A Well". The Fultz patent shows a device known as a dump bailer for dumping material into a well and includes a tubular body adapted to be lowered into the well, a frangible seal closing the lower end of the tubular body, a rod passing through the lower portion of the tubular body below the seal and movable therein, the rod being in position to move upwardly to break the frangible seal upon contact of the rod with the bottom of the well, and a piston is disposed within the tubular body above the viscous liquid in the body, and a latch on the body initially holds the piston stationary in the upper end of the tubular body and the latch can be released from the piston after the tubular body reaches the bottom of the well.
U.S. Pat. No. 2,696,258 issued to H. M. Green entitled "Oil Well Cementing Packer" provides a vertically elongated container for depositing cement in a zone within a well bore and features a gas generating charge adapted upon ignition to displace through a lower outlet in the container and into the zone. Another patent that relates to the completion of wells and the use of gravel is U.S Pat. No. 2,635,595 entitled "Well Completion" wherein gravel or other material of desired particle sizes placed between the producing formation and a screen member in such a way that oil or other fluid produced passes through the gravel and into the screen member. A positive means is provided for avoiding the existence of unfilled cavities in the gravel packed section into which the gravel may move such as, the space resulting from bridging of gravel or because the gravel is deposited by the circulation method. In the Greene U.S. Pat. No. 2,696,259 entitled "Apparatus For Firing Propellant Charges In a Well", there is provided a means for depositing cement in a well bore.
The controlling of sand in wells has been the subject of several patents. The Abendroth U.S. Pat. No. 2,775,303 entitled "A Method For Controlling Sand and Wells", provides a method for setting gravel packs suitable for use in wells in which a tubing string is arranged. In the Killingsworth U.S. Pat. No. 2,896,714 entitled "Gravel Packing of Wells", there is shown an improvement for obtaining a gravel pack around a screen pipe or perforated liner in an oil well, the gravel pack completely filling an enlarged cavity around the perforated liner or screen pipe. As part of the method, a bailer is run into the well on a wireline and enters the interior of the liner. The liner is prevented from rotating by means of the frictional resistance offered by the gravel and the centering bow springs and centralizers. Another patent issued to Greene entitled "Apparatus For Depositing Cement or Like in a Well" describes a tool assembly to be lowered into a well on a flexible line and includes a container having a mass of material therein and an opening at the lower portion of the container for dispensing the material such as cement into the well.
The Jones U.S. Pat. No. 3,428,128 entitled "Method and Apparatus For Use in Gravel Packing Wells" provides a method wherein a gas previous basket is lowered into a producing zone, the basket having a plurality of compressed staves. Gravel is placed in the area beneath the basket adjacent the producing zone. The staves are released from the basket so that the staves assume a position in contact with the casing at points substantially around the periphery of the casing, the base of the tasket being located above the points and the well is produced whereby the fluids flow from the producing zone through the gravel into the production conduit, the gravel being retained in position adjacent the producing zone by the basket while entrapped gases in the formation may be passed upwardly through the basket.
The Burrows U.S. Pat. No. 4,635,725 entitled "Method and Apparatus For Gravel Packing a Well" provides a perforated liner in a well that includes a wash pipe carried by a cross-over tool which has a pair of fluid passages through it. Flow of fluid may be reversed. The wash pipe is mounted in a floating relation with the liner for vertical movement and a double acting piston mounted between the liner and washpipe which is responsive to fluid pressure within the liner for moving the washpipe vertically relative to the liner.
U.S Pat. No. 4,618,163 entitled "Sand Control System" provides a well bore sand control and filtration system, method and apparatus for controlling formation sands and for preventing the influx of formation sands into the well bore, into the production string and into the produced fluids. The system includes introducing smooth particles in the well bore with limited or no pumping either of particles or of fluids with the particles, introducing the production string into the wellbore with the bottom of the string being introduced into the accumulation of smooth particles and the bottom of the string having connected thereto a tool permitting flow of formation fluids into the production string. The tool moves into the accumulation of particles forcing particles into the perforation tunnels extending from the annulus through the casing and cement into the formation. The system method and apparatus may also be used in an open, uncased, uncemented hole.
A well screen filter formed with inner and outer concentric screens defining an annular filtering space filled with filtrating medium is the subject of U.S. Pat. No. 4,693,318 entitled "Sand Control Devices and Method of Installation Thereof" issued to Petrovich. A gravel packing apparatus and method is the subject of U.S. Pat. No. 4,700,777 entitled "Gravel Packing Apparatus and Method", issued to Luers. The apparatus provided in the '777 patent is for placing a screen filter in for packing gravel around the filter screen adjacent a well formation. The apparatus includes a body having a packer portion and a valve portion. The body defines a central passageway therethrough. The valve portion includes a valve mandrel with a valve sleeve slideably positioned therein, and transverse openings in the valve sleeve and valve mandrel are aligned to form a transverse passageway therethrough when the valve is in an open position. A stinger is positionable in the body for closing the central passageway and actuating the valve sleeve between the open and closed positions thereof. When in the open position, the transverse openings in the valve mandrel and valve sleeve are aligned with a transverse opening in the stinger such that fluid communication is provided between a well annulus below the packer portion and the tool string above the apparatus. Fingers engage the stinger so that when the stinger is moved from the body, the valve is closed. The stinger has seal members thereon, and the stinger may be positioned such that the transverse opening therein is above the packer portion while at least one seal element is still sealingly engaged with the central passageway. In this way, fluid communication is provided between the tool string and a well annulus above the packer. When the stinger is removed from the body, the central passageway is opened for production of fluids therethrough. A method for using the apparatus is also disclosed.